Sable and umbrous mice

Summary An umbrous gene in the house mouse is described which is transmitted in crosses as a simple dominant. The same gene is capable of engendering a sable phenotype with yellow and an umbrous-agouti with white-bellied agouti. It assorts independently of the agouti locus, with which it was specifically tested, and probably of sex. The manifestation of the gene is briefly contrasted with other known cases of umbrous heredity.